The rules proposed by the Department of Conservation follow the massive Southern California Gas Co. leak capped last year that persisted nearly four months and led to widespread complaints of headaches, nosebleeds, nausea and other maladies.

Ken Harris, supervisor of the department's oil and gas division, said the regulations aimed at making all 12 underground natural gas storage fields in the state safer are believed to be the strictest and most comprehensive in the nation.

The agency had been criticized for being easy on industry before the October 2015 blowout at the Aliso Canyon facility above the suburbs of the San Fernando Valley.

Proposed regulations intended at preventing future leaks would set standards for stronger well construction, daily testing for leaks and more rigorous inspections of well integrity. It would also require emergency response plans and contingencies for disasters such as earthquakes, spills, explosions or fires.

Wells would also need to have secondary protection from a leak.

The well that failed was being used to inject and withdraw natural gas through both an internal pipe and an outer steel casing intended as a protective layer.

The method, which is employed throughout the industry, allowed larger volumes of gas to pass through both spaces, but put the system in jeopardy if there was a leak, experts said.

The Aliso Canyon blowout is believed to have occurred when the protective outer casing failed in a well that was over 60 years old. Gas under high pressure escaped and forced its way from a depth of 900 feet to the surface where it couldn't be contained for months.

The proposed regulations would overlap with some of the stiffer requirements put in place at Aliso Canyon, where 45 of utility's 114 wells have now passed rigorous tests and the remaining wells are out of operation.

Regulators are still weighing whether to let SoCalGas, a subsidiary of San Diego-based Sempra Energy, resume operations at the facility.

Many residents who live in nearby Porter Ranch and environmental groups want the facility to be shut down, though SoCalGas said it's a vital energy source in the region.

A spokesman said the company was reviewing the proposed regulations, which are open to public comment until July 13.